A power supply powered from the utility grid is susceptible to disturbances on the utility voltage, which includes, for example, brown outs and line outages. In some applications, it may be preferable for a power supply to continue to deliver output power even when the input voltage has dropped to zero for one fundamental line cycle (e.g. about 16 msec at 60 Hz and about 20 msec at 50 Hz). Capacitors may be used as energy storage elements to provide power during disturbances on the power line. In general, more capacitance is required with higher output power and higher minimum voltage requirements.
Power conversion losses may account for about 50% of the wattage utilized in modern day data centers resulting in reduced server density and low rack utilization. Overall the power and cooling capacity available to silicon loads for information processing is greatly reduced which in turn increases the total cost of ownership (TCO) of data centers. Efficient power delivery may be important to reduce power consumption, increase server density and also provide increased MIPS/watt metric for server applications.